Bladed rotor with means to supply fluid to passages in the blades



Nov. 28, 1961 Filed Sept. 10, 1956 A. B. EV ETT BLADED OR TH MEA TOSUPPLY FLUID FA GES IN THE BLADES 4 Sheets-Sheet 1 Nov. 28, 1961 BLADEDlgT Filed Sept. I 10, 1956 I I I Hi 1. j 56 A. B. EVERET OR WITH MEANSPASSAGES IN T su Y FLUID BLA 4 Sheets-Sheet 2 Nov. 28, 1961 A. B.EVERETT 3,010,696

- BLADED OR WITH MEANS SUPPLY FLUID PASSAGES IN T BLADES Filed Sept. 10,1956 4 Sheets-Sheet 3 Nov. 28, 1961 A. B. EVERETT 3,

BLADED ROTOR WITH MEANS SUPPLY FLUID TO PASSAGES IN T BLADES Filed Sept.10, 1956 4 Sheets-Sheet 4 United States Patent 3,010,696 BLADED ROTORWITH MEANS T0 SUPPLY FLUID TO PASSAGES IN THE BLADES Anthony BernardEverett, Littleover, England, assignor to Rolls-Royce Limited, Derby,England, a British comp y Filed Sept. 10, 1956, Ser. No. 608,897 Claimspriority, application Great Britain Sept. 26, 1955 6 Claims. (Cl.253-3915) This invention relates to axial-flow fluid machines, such forinstance as axial-flow turbines or compressors as used in gas-turbineengines, of the class which has a rotor comprising a rotor disc and aring of blades mounted on the periphery of the disc by means of extendedblade roots which include shouldered attachment portions engaging in thedisc and outwardly-extending portions defining a series ofaxially-extending spaces radially inwards of the working fluid passageof the machine. Such a bladed rotor will be referred to as a bladedrotor as set forth.

It is often desirable, for instance for the purpose of cooling turbinerotor blades, to deliver a fluid to passages formed within the blades,and this invention has for an object to provide improved means forsupplying a fluid to such passages.

According to the present invention, a bladed rotor as set forth isprovided with blades which have fluid flow passage means therein, atleast one end of the passage means in each blade opening to one of theaxiallyextending spaces between its root and the roots of the adjacentblades, and with an annular plate which is mounted on the rotor disc inspaced relation to the disc periphery to define an annular manifoldspace which communicates with the passage means, and which defines withthe disc a path for the supply of fluid to the manifold space from apoint at lesser radius than the manifold space.

In one preferred construction according to this invention, each bladealso has another end of the flow passage means opening through anaxially-facing surface of the root portion to the manifold space toreceive fluid therefrom, the fluid flowing from the passages at said oneend thereof into said axially-extending spaces which are blanked oflfrom the manifold space.

In another preferred construction according to this invention, said oneend of the passage means in each blade opens to the axially-extendingspace to one side of the root of the blade and the other end of thepassage means opens to the axially-extending space on the opposite sideof the root, one of said spaces being open to the manifold space and theother being blanked-off from the manifold space.

According to a feature of this invention applicable to either of thepreferred constructions just set forth, the bladed rotor may comprise afurther annular plate mounted on the rotor disc between themanifold-spaceforming plate and the disc periphery and in contact withthe disc periphery and blade roots to cover the adjacent ends of theaxially-extending spaces, there being holes in the further annularplate, which holes in the first-mentioned preferred constructionregister with the ends of the passage means where they open to theaxially-facing surfaces of the blade roots and which holes in the secondpreferred arrangement are aligned with alternate ones of theaxially-extending spaces between the blade roots so that some of thespaces serve to feed fiuid to the passage means in the blades and othersserve to receive the fluid after it has flowed through the blades. Thefurther plate may be flexible so that where fluid under high pressure issupplied to the manifold spaces this plate is loaded firmly into contactwith the rotor disc periphery and the blade roots.

According to another feature of this invention applicable to thepreferred arrangements above set forth, there may be provided an annularsealing plate mounted on the periphery of the rotor disc to close theends of the axially-extending spaces between the roots which are remotefrom the manifold space.

According to yet another feature of this invention, thernanifold-space-defining plate may be provided at a radius less thanthat of its outer periphery with a part aifordin'g the rotating elementof a labyrinth seal which part'is adapte d to co-operate with stationarystructure of the fluid machine to define a closed chamber from whichpressurefluid is fed to the path between the manifoldspace-definingplate and the rotor disc.

Two preferred embodiments of this invention will now b described inwhich cooling air is Supplied under pressure to the rotor blades of aturbine of a gas-turbine engine. The description refers to theaccompanying draw.- ings in which.

FIGURE *1 is an axial view of one form of turbine rotor with partsbroken away to show details of con a c on,

FIGURE 2 is a section on the line 2-2 of FIGURE 1,

7 FIGURE. 3 is a view in the direction of arrow 3 on FIGURE 2,

FIGURE4 is a section on the line 44 of FIGURE 3,

FIGURE 5 is an axial section t rough the second embodiment,

FIGURE 6 is. asection on the line 66 of FIGURE 5,

Each blade 11 comprises an operative portion 11;;-

which extends radially across the working fluid passage of the turbine,a tip shroud 12 at the radially-outer end of the operative portion 11a,and a root portion at the.

radiallydnner end of the blade. The root portion comprises a shoulderedattachment portion 13 which occupies a correspondingly-shaped groove inthe disc periphery to retain the blade radially in position, a platformportion 14 from which the operative portion 11a of the blade projectsand which with the platform portions of the remaining blades forms anannular part of the wall of the working fluid passage of the turbine,and a stem 15 by which the platform portion '14 is connected to theattachment portion 13. The stem is ciroumferentially narrower thaneither the attachment portion 13 or the platform portion 14, and so whenthe blades are mounted: in the disc periphery axially-extending spacesare leftv between the stems 15. The blades 11 are prevented frombecoming detached from the disc by rearward axial displacement by beingprovided at one end with t-angs' 1'6 which bear against oneaxially-facing surface of the disc 10 and are retained against forwarddisplacement by a retaining plate :17 which lies against the otheraxiallyfacing surface of the disc 10 and against the adjacent ends ofthe rootrportions of the blades 11. The retaining plate 17 also servesto close oft the downstream ends of the axially-extending spaces betweenthe stems 15.

Each blade is provided internally with passages for conveying coolingfluid, In the arrangement illustrated each blade 11 has a first passage18 adjacent its leading edge, a second passage 19 adjacent its trailingedge, and I a third passage 20 at its mid-section, these passagesextend- Patented Nov. 28, 19st FIGURE 7 is a view on the line 7-7 ofFIGURE 5,,

3. ing lengthwise of the operative portion 11a of the blade. Thepassages 18, 19 and 20 are joined together adjacent the tip of the bladeby a cross passage 21. The passages 18 and 19 have extensions 18a, 19ain the stern of the root portion and these extensions meet in a port 22formed in the upstream axially-facing surface of the stem 15. Thepassage 20 also extends into the stem and opens through a port 23 to oneof the circumferentially-facing surfaces of the stem 15. In operation,cooling air is fed to the blade through the port 22 and flows outwardlythrough the passages 18 and 19 and then flows inwardly through thepassage 20 and out through the port 23 into the axially-extending spacebetween a pair of stems 15. Thence the cooling air passes outward intothe working fluid passage of the turbine through small circumferentialgaps between adjacent platforms 14, thus preventing the inflow of heatedworking fluid into the axially-extending spaces.

The cooling air is fed to the blades in the following.

way.

There is provided on the upstream face of the turbine disc meansaffording a manifold which is supplied with air under high pressure andwhich is in communication with the ports 22 in the stems of the blades11.

This means comprises a first annular plate 24 of flat annular form whichis adapted to lie against the upstream axially-facing surface of theperiphery of the rotor" disc 10 and the adjacent end surfaces of theroot portions of the blades 11. The plate 24 is provided with acontinuous axial flange 25 at its outer radius, with a ring of holes 26(FIGURE 1) one to register with each of the ports 22, with a series ofradially-extending slots 27 which extend from the radially-inner edge ofthe plate 24 and which when the plate is in position engage over thetangs 16, and with a series of ciroumferentiallyspaced axial tongues 28which extend away from the surface of the disc. 1

The manifold-affording means also comprises a second annular plate 29which is of substantially greater radial extent than the plate 24. Theradially-outer edge of the plate 29 is formed with a peripheral bead 30which is offset from the plane of the plate 29 so that when the plateis'in position on the disc the bead 30 fits outside the axial flange 25at the outer edge of the plate 24 and also engages behind radiallyinwardly-projectin-g flanges 31 on the upstream edges of the platformportions 14. When the plate 29'is in position the flange 25 and thetongues 28 hold the outer portion of the plate 29 away from the mainbody of the plate 24.

At about its mid-radius, the plate 29 is provided with a number ofcircumferentially-spaced lands 32 which provide seats for the heads ofretaining bolts 33 which pass through the plate 29 and engage in nuts 34trapped in the structure of the rotor disc 10. The nuts 34 are ofT-section in planes axially of the disc 10 (see FIGURE 2) and they arereceived in correspondingly-shaped grooves in axial projections 35outstanding from the upstream surface of the rotor disc 10. The plate 29is also provided with an annular axially-directed flange 36 to engagethe radially-inner surfaces of the axial projections 35.

At its inner radius the plate 29 is provided with a second series oflands 37 through which project stems of a second series of bolts 38 toengage in T-section nuts 39 trapped in a second series ofcircumferentiallyspaced axial projections 40, the lands 37 abuttingagainst the projections 40.

At its inner edge the disc 29 is provided with an axiallyprojeotingflange 41 having on its radially-outer surface a series ofaxially-spaced ribs 42 so as to provide the rotating element of alabyrinth seal, the stationary element of which is formed by a part ofthe stator structure 43. The labyrinth seal is employed to preventexcessive leakage of high-pressure air fed to the chamber 44 formedbetween the radially inner portion of the upstream surface of the rotordisc 10 and adjacent stator structure, and it will be appreciated thatsince the labyrinth seal is at a relatively small radius from the axisof rotation the leakage area through it for a given clearance betweenthe ribs 42 and the stator structure 43 is correspondingly reduced.

In operation, pressure air flows from the chamber 44 outwardly,circumferentially between the projections 49 and the projections 35,into the fluid supply manifold space 45 formed between the plate 24 andthe outer portion of the plate 29. The pressure air then flows throughthe holes 26 and ports 22 into the passages 18 and 19 in the blades andthence through passages 20 and ports 23 into the axially-extendingspaces between the stems 15. The cooling air leaks from these spacesthrough the circumferential clearances between the platform portions 14into the working fluid passage of the turbine and thus prevents hot gasfrom flowing inwardly into these spaces.

Preferably the plate 24 is made flexible so that it is loaded by thehigh-pressure air within the manifold space 45 firmly into contact withthe adjacent surfaces of the turbine'disc 10 and blade roots, thuspreventing leakage ofcooling air direct from the holes 26 into theaxiallyextending spaces between the stems 15.

The projections 3-5 and 40 are conveniently formed on the rotor disc 10by providing a continuous rib on the disc 10, milling a groove ofappropriate T-section in the rib and then machining away the rib atintervals to leave the projections.

Referring now to FIGURES 3 and 4, there is illustrated a convenient wayof closing off the radially-outer ends of the passages 18, 19 and 20after formation of the cross passage 21. For this purpose the crosspassage 21 is formed by milling a slot in the tip shroud 12, and byforming the shroud with a dovetail groove extending across it above thepassage 21 to receive a closure plate 46. The closure plate 46 is slidinto position along the dovetail groove 21 and is tack-welded inposition. It will be seen that the tip shroud is provided with featuresafiording tip seals to co-operate with stator structure, and it will beunderstood that the cover plate 46 will have its external surfacecorrespondingly shaped.

Referring now to FIGURES 5 to 8, there is shown a turbine rotor disc 50having blades 51 mounted at its periphery. Each blade has an operativeportion 51a, a tip shroud 52 and a root portion which comprises anattachment portion 53, a blade platform 54 and a stem 55 joining theattachment portion 53 and platform 54. The stems are circumferentiallynarrower than the platforms and attachment portions and so a series ofaxiallyextending spaces 56 are formed between them.

Each blade 51 has internal passages extending lengthwise through it,there being a passage 57 at its upstream edge, a passage 58 at itsdownstream edge, and a passage 59 at its mid chord. The passages 57, 58,59 are joined at the tip of the blade by a transverse passage 60, and attheir inner ends, the passages 57, 58 open into the space 56 to one sideof the stem 55 and the passage 59 opens to the space 56 on the otherside of the stem. It is arranged that passages 57, 58 open to alternatespaces 56 and that the passages 59 open to the remaining spaces 56.

Each blade 51 has a tang 62 at one end of its attachment portion to abutthe disc rim and prevent detachment in one direction and an annularplate 63 is mounted on the downstream surface of the rotor to retain theblades against detachment in the opposite sense. The plate 63 closes thedownstream ends of the spaces 56.

Cooling air is supplied to the blades in the following way. A firstannular plate 64 is mounted on the upstream face of the rotor. Thisplate has a continuous axially-narrow flange 65 at its radially outeredge, a

' series of holes 66 which open into the upstream ends and at its inneredge a series of radial tongues 67 each of which projects between a pairof the tangs 62. Each of the tongues 67 has at its free ends an axiallythickened portion 68 with a central projecting rib 69, the majority ofwhich portions 68 are radially narrow but a diametrically-opposite pairof which 68a are radially of greater extent.

A second annular plate 70 of substantially greater radial dimension thanplate 64 is mounted on the rotor to form with the plate 64 a cooling airdistribution manifold. The plate 70 has at its outer edge a peripheralhead 71 which is offset from the plane of plate 70 so as to fit outsidethe flange 65 of plate 64 and behind radially-inwardly-projectingflanges 72 on the platforms 54. At a position radially within the tangs62, the plate 70 is provided with a ring of circumterentially-spacedhooked, axially projections 73 which engage behind correspondingprojections 74 on the turbine disc 70. At its inner radius, the plate 70has a thickened portion 79a and bears against cireumferentially-spacedpairs of projections 75 on the disc 50. Dowel pins 76 pass through theportion 70a of the plate 70 and each pin 76 engages between a pair ofthe projections 75. Each pin 76 has a tongue 77 at its outer end whichprojects into a corresponding notch 78 in bead 79 formed around theportion 70a of the plate 70, and the bead has an inwardly-facing channelreceiving a spring retaining ring 80 which overlies the tongues 77 toretain the dowel pins in position. The portion 70a also hascircumferentially-spaced radially-inwardly projecting dogs 81 whichengage behind correspondingly-spaced hooked projections 82 on theturbine disc 50.

The disc 70 also has an axially-projecting annular flange 83 extendingfrom its upstream surface at a radius between its inner and outer edges,and the flange is formed with axially-spaced ribs 84. The ribs 84cooperate with an annular member 85 which is part of the stationarystructure of the turbine, to form a labyrinth seal preventing excessiveleakage of pressure air from a chamber 86 formed between the inner partof plate 70 and stationary structure 87 and fed with pressure airthrough duct 88.

In operation air flows from chamber 86 between the pairs of projections75 into space 89 and outwardly from the space 89 past projections 73, 74and ribs 69 into the fluid supply manifold space 90 formed between theouter portion of plate 70 and plate 64. From the manifold space 90, theair passes through holes 66 into alternate spaces 56 and thence throughpassages 57, 58, passages 60 and passages 59 into the remaining spaces56. The air leaves these latter spaces through the clearance gapsbetween the platforms 54.

In either of the two arrangements just described, the annular plate 17,63 may be provided with exit passages which communicate with the exitspaces between the blade stems. I

Iclaim:

1. A bladed rotor for an axial-flow fluid machine, which rotor comprisesa rotor disc having an outer peripheral rim, a plurality of rotorblades, each blade having a root, the root of each blade comprising ashouldered attachment portion with radially-facing shoulders, a platformportion and a stem portion extending from the shouldered attachmentportion to the platform portion, the said rim having therein slotsextending across the rim and receiving the shouldered attachmentportions, said slots having radially-facing shoulders complementary tothe shoulders of the attachment portions whereby the blades are retainedradially in position on the rim with their stem portions projectingradially outwards from the rim, the stem portions beingcircumferentially narrower than the attachment portions and definingspaces extending axially between them, the

blades having in them internal fluid passages having inlets thereto andoutlets therefrom in the stem portions, at least the outlets of thepassages in the blades opening into the axially-extending spaces definedby the stem portions and platform portions of the blade roots, a firstannular plate mounted on the disc rim in contact therewith and incontact with the attachment portions and the stem portions and closingthe adjacent ends of the axially-extending spaces into which saidoutlets open, and a second annular plate mounted on the disc inaxially-spaced relation thereto and extending radially over the firstannular plate in axially-spaced relation, the space between the annularplates forming a fluid supply manifold for cooling air, there beingapertures in said first annular plate placing the manifold incommunication with said inlets, and said second annular plate having agreater radial extent than the first annular plate and extendingradially inwards of the first annular plate and of the rim and definingwith the disc a fluid path extending radially outwards from a positionat a less radius than the rim to the manifold, said platform portionshaving means communicating with the anally-extending spaced defined bysaid stem and platform portions so that the cooling air is exhaustedbetween said platform portions.

2. A rotor according to claim 1, wherein the said outlets open intoalternate ones of the axially-extending spaces and the said inlets openinto the remaining axiallyextending spaces, the apertures in the firstannular plate opening into the said remaining axially-extending spaces,and wherein there is provided a further plate which is mounted on therim in contact therewith and in contact with the root attachmentportions and stem portions, said further plate closing oii the ends ofthe axially-extending spaces remote from the first annular plate.

3. A rotor according to claim 1, wherein said apertures in the firstannular plate are in portions of the plate in contact with the stemportions and the said inlets open through the stem portions in registerwith the apertures, the first annular plate closing 01? the adjacentends of all the axially-extending spaces and the outlet of the fluidpassage of each blade opening to the axially-extending space on one sideof its stem portion.

4. A bladed rotor as claimed in claim 1, comprisingradially-inwardly-projecting flanges on the blade roots adjacent thefirst and second annular plates, said first annular plate having acontinuous axial flange at its outer edge and the second annular platehaving at its outer edge a peripheral head which axially overlaps andfits outside the continuous axial flange and engages axially behind saidflanges on the blade roots.

5. A bladed rotor as claimed in claim 1, wherein the second annularplate is provided at a radius less than that of its outer periphery witha part affording the rotating element of a labyrinth seal.

6. A bladed rotor as claimed in claim 1, wherein said first annularplate is flexible so that Where fluid under high pressure is supplied tothe manifold space, the said further plate is loaded firmly into contactwith the rotor disc periphery and the blade roots.

References Cited in the file of this patent UNITED STATES PATENTS

